The invention relates generally to measuring shaft torque, and more particularly to a method of measuring long shaft torque that eliminates errors due to long shaft skew.
It is old in the prior art to measure shaft torque by means of phase shift between sine wave signals from similarly recorded magnetic tapes spaced longitudinally apart on a torque loaded shaft. The magnetic tapes and heads were always subject to frictional wear, and the results always reflected errors due to shaft skew. Attention is invited to U.S. patents to Schindler, U.S. Pat. No. 3,935,733 of which this application is an improvement; to Pratt U.S. Pat. No. 3,871,215; to Holden U.S. Pat. No. 2,586,540; to Bart U.S. Pat. No. 3,604,255; and British patent to DeHaviland U.S. Pat. No. 968,503.